I have a Gibson ES 135 to which I have fitted a Bigsby unit. Since fitting the Bigsby, I have had problems with the guitar's original bridge - a Gibson ABR1 - namely with tuning problems and string breakages.
I'm not a fan of the ABR1 anyway; the saddles have sharp edges which frequently cut my hands and cause strings to break, and they are rattly and made of cheap materials. Lots of people have improved the design over the years and yet they still find their way on to expensive Gibson guitars, strangely.
I had been meaning to replace my bridge ever since fitting the Bigsby, but when I broke two strings in one gig the other night, I decided the time had come.
I came across the ABM on Thomann after comparing a few designs. I wasn't previously aware of it, but it looked great and, more importantly, had all the right dimensions (radius, string spacing, intonation adjustment), so I ordered one.
It's not cheap compared to other roller bridges, but then it's machined from bell brass, not die cast from zinc, like most others. When it arrived, I was delighted with the quality - even better than it appeared in the photos. This bridge is BEAUTIFULLY made. It fitted my guitar perfectly (amazingly, it needed practically no adjustment for perfect intonation!) and feels really comfortable under my strumming hand, due to the complete lack of sharp edges.
I'm not going to comment on whether brass is sonically superior to cast zinc, as I'm not qualified to do so, other than to say it sounds great to me. No dead spots; a full, even response across the strings and neither noticeably brighter nor darker than before.
Most importantly, my tuning is now incredibly stable (no creaks or pings when using the Bigsby, either) and I have yet to break a single string.
Thoroughly recommended and worth every penny.